Re: [RESEND PATCH v2] ARM64: ACPI: Update documentation for latest specification version

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On Wed, Mar 16, 2016 at 10:20:23AM +0530, Vikas Sajjan wrote:
> On Wed, Mar 16, 2016 at 1:58 AM, Al Stone <al.stone@xxxxxxxxxx> wrote:
> > The ACPI 6.1 specification was recently released at the end of January 2016,
> > but the arm64 kernel documentation for the use of ACPI was written for the
> > 5.1 version of the spec.  There were significant additions to the spec that
> > had not yet been mentioned -- for example, the 6.0 mechanisms added to make
> > it easier to define processors and low power idle states, as well as the
> > 6.1 addition allowing regular interrupts (not just from GPIO) be used to
> > signal ACPI general purpose events.
> >
> > This patch reflects going back through and examining the specs in detail
> > and updating content appropriately.  Whilst there, a few odds and ends of
> > typos were caught as well.  This brings the documentation up to date with
> > ACPI 6.1 for arm64.
> >
> > RESEND:
> >    -- Corrected From: header and added missing Cc's
> >
> > Changes for v2:
> >    -- Clean up white space (Harb Abdulhahmid)
> >    -- Clarification on _CCA usage (Harb Abdulhamid)
> >    -- IORT moved to required from recommended (Hanjun Guo)
> >    -- Clarify IORT description (Hanjun Guo)
> >
> > Signed-off-by: Al Stone <al.stone@xxxxxxxxxx>
> > Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
> > Cc: Will Deacon <will.deacon@xxxxxxx>
> > Cc: Jonathan Corbet <corbet@xxxxxxx>
> > ---
> >  Documentation/arm64/acpi_object_usage.txt | 445 ++++++++++++++++++++++--------
> >  Documentation/arm64/arm-acpi.txt          |  28 +-
> >  2 files changed, 356 insertions(+), 117 deletions(-)
> >
> > diff --git a/Documentation/arm64/acpi_object_usage.txt b/Documentation/arm64/acpi_object_usage.txt
> > index a6e1a18..29bc1a1 100644
> > --- a/Documentation/arm64/acpi_object_usage.txt
> > +++ b/Documentation/arm64/acpi_object_usage.txt
> > @@ -11,15 +11,16 @@ outside of the UEFI Forum (see Section 5.2.6 of the specification).
> >
> >  For ACPI on arm64, tables also fall into the following categories:
> >
> > -       -- Required: DSDT, FADT, GTDT, MADT, MCFG, RSDP, SPCR, XSDT
> > +       -- Required: DSDT, FADT, GTDT, IORT, MADT, MCFG, RSDP, SPCR, XSDT
> >
> > -       -- Recommended: BERT, EINJ, ERST, HEST, SSDT
> > +       -- Recommended: BERT, EINJ, ERST, HEST, PCCT, SSDT
> >
> > -       -- Optional: BGRT, CPEP, CSRT, DRTM, ECDT, FACS, FPDT, MCHI, MPST,
> > -          MSCT, RASF, SBST, SLIT, SPMI, SRAT, TCPA, TPM2, UEFI
> > +       -- Optional: BGRT, CPEP, CSRT, DBG2, DRTM, ECDT, FACS, FPDT, MCHI,
> > +          MPST, MSCT, NFIT, PMTT, RASF, SBST, SLIT, SPMI, SRAT, STAO, TCPA,
> > +          TPM2, UEFI, XENV
> >
> > -       -- Not supported: BOOT, DBG2, DBGP, DMAR, ETDT, HPET, IBFT, IVRS,
> > -          LPIT, MSDM, RSDT, SLIC, WAET, WDAT, WDRT, WPBT
> > +       -- Not supported: BOOT, DBGP, DMAR, ETDT, HPET, IBFT, IVRS, LPIT,
> > +          MSDM, OEMx, PSDT, RSDT, SLIC, WAET, WDAT, WDRT, WPBT
> >
> >
> >  Table  Usage for ARMv8 Linux
> > @@ -50,7 +51,8 @@ CSRT   Signature Reserved (signature == "CSRT")
> >
> >  DBG2   Signature Reserved (signature == "DBG2")
> >         == DeBuG port table 2 ==
> > -       Microsoft only table, will not be supported.
> > +       License has changed and should be usable.  Optional if used instead
> > +       of earlycon=<device> on the command line.
> >
> >  DBGP   Signature Reserved (signature == "DBGP")
> >         == DeBuG Port table ==
> > @@ -133,10 +135,11 @@ GTDT   Section 5.2.24 (signature == "GTDT")
> >
> >  HEST   Section 18.3.2 (signature == "HEST")
> >         == Hardware Error Source Table ==
> > -       Until further error source types are defined, use only types 6 (AER
> > -       Root Port), 7 (AER Endpoint), 8 (AER Bridge), or 9 (Generic Hardware
> > -       Error Source).  Firmware first error handling is possible if and only
> > -       if Trusted Firmware is being used on arm64.
> > +       ARM-specific error sources have been defined; please use those or the
> > +       PCI types such as type 6 (AER Root Port), 7 (AER Endpoint), or 8 (AER
> > +       Bridge), or use type 9 (Generic Hardware Error Source).  Firmware first
> > +       error handling is possible if and only if Trusted Firmware is being
> > +       used on arm64.
> >
> >         Must be supplied if RAS support is provided by the platform.  It
> >         is recommended this table be supplied.
> > @@ -149,20 +152,27 @@ IBFT   Signature Reserved (signature == "IBFT")
> >         == iSCSI Boot Firmware Table ==
> >         Microsoft defined table, support TBD.
> >
> > +IORT   Signature Reserved (signature == "IORT")
> > +       == Input Output Remapping Table ==
> > +       arm64 only table, required in order to describe IO topology, SMMUs,
> > +       and GIC ITSs, and how those various components are connected together,
> > +       such as identifying which components are behind which SMMUs/ITSs.
> > +
> >  IVRS   Signature Reserved (signature == "IVRS")
> >         == I/O Virtualization Reporting Structure ==
> >         x86_64 (AMD) only table, will not be supported.
> >
> >  LPIT   Signature Reserved (signature == "LPIT")
> >         == Low Power Idle Table ==
> > -       x86 only table as of ACPI 5.1; future versions have been adapted for
> > -       use with ARM and will be recommended in order to support ACPI power
> > -       management.
> > +       x86 only table as of ACPI 5.1; starting with ACPI 6.0, processor
> > +       descriptions and power states on ARM platforms should use the DSDT
> > +       and define processor container devices (_HID ACPI0010, Section 8.4,
> > +       and more specifically 8.4.3 and and 8.4.4).
> >
> >  MADT   Section 5.2.12 (signature == "APIC")
> >         == Multiple APIC Description Table ==
> >         Required for arm64.  Only the GIC interrupt controller structures
> > -       should be used (types 0xA - 0xE).
> > +       should be used (types 0xA - 0xF).
> >
> >  MCFG   Signature Reserved (signature == "MCFG")
> >         == Memory-mapped ConFiGuration space ==
> > @@ -176,14 +186,38 @@ MPST   Section 5.2.21 (signature == "MPST")
> >         == Memory Power State Table ==
> >         Optional, not currently supported.
> >
> > +MSCT   Section 5.2.19 (signature == "MSCT")
> > +       == Maximum System Characteristic Table ==
> > +       Optional, not currently supported.
> > +
> >  MSDM   Signature Reserved (signature == "MSDM")
> >         == Microsoft Data Management table ==
> >         Microsoft only table, will not be supported.
> >
> > -MSCT   Section 5.2.19 (signature == "MSCT")
> > -       == Maximum System Characteristic Table ==
> > +NFIT   Section 5.2.25 (signature == "NFIT")
> > +       == NVDIMM Firmware Interface Table ==
> >         Optional, not currently supported.
> >
> > +OEMx   Signature of "OEMx" only
> > +       == OEM Specific Tables ==
> > +       All tables starting with a signature of "OEM" are reserved for OEM
> > +       use.  Since these are not meant to be of general use but are limited
> > +       to very specific end users, they are not recommended for use and are
> > +       not supported by the kernel for arm64.
> > +
> > +PCCT   Section 14.1 (signature == "PCCT)
> > +       == Platform Communications Channel Table ==
> > +       Recommend for use on arm64, and required when using CPPC to control
> > +       power on the platform.
> > +
> > +PMTT   Section 5.2.21.12 (signature == "PMTT")
> > +       == Platform Memory Topology Table ==
> > +       Optional, but useful, but not currently supported.
> > +
> > +PSDT   Section 5.2.11.3 (signature == "PSDT")
> > +       == Persistent System Description Table ==
> > +       Obsolete table, will not be supported.
> > +
> >  RASF   Section 5.2.20 (signature == "RASF")
> >         == RAS Feature table ==
> >         Optional, not currently supported.
> > @@ -195,7 +229,7 @@ RSDP   Section 5.2.5 (signature == "RSD PTR")
> >  RSDT   Section 5.2.7 (signature == "RSDT")
> >         == Root System Description Table ==
> >         Since this table can only provide 32-bit addresses, it is deprecated
> > -       on arm64, and will not be used.
> > +       on arm64, and will not be used.  If provided, it will be ignored.
> >
> >  SBST   Section 5.2.14 (signature == "SBST")
> >         == Smart Battery Subsystem Table ==
> > @@ -207,7 +241,7 @@ SLIC   Signature Reserved (signature == "SLIC")
> >
> >  SLIT   Section 5.2.17 (signature == "SLIT")
> >         == System Locality distance Information Table ==
> > -       Optional in general, but required for NUMA systems.
> > +       Optional in general, but required for arm64 NUMA systems.
> >
> >  SPCR   Signature Reserved (signature == "SPCR")
> >         == Serial Port Console Redirection table ==
> > @@ -220,7 +254,7 @@ SPMI   Signature Reserved (signature == "SPMI")
> >  SRAT   Section 5.2.16 (signature == "SRAT")
> >         == System Resource Affinity Table ==
> >         Optional, but if used, only the GICC Affinity structures are read.
> > -       To support NUMA, this table is required.
> > +       To support arm64 NUMA, this table is required.
> >
> >  SSDT   Section 5.2.11.2 (signature == "SSDT")
> >         == Secondary System Description Table ==
> > @@ -235,6 +269,11 @@ SSDT   Section 5.2.11.2 (signature == "SSDT")
> >         These tables are optional, however.  ACPI tables should contain only
> >         one DSDT but can contain many SSDTs.
> >
> > +STAO   Signature Reserved (signature == "STAO")
> > +       == _STA Override table ==
> > +       Optional, but only necessary in virtualized environments in order to
> > +       hide devices from guest OSs.
> > +
> >  TCPA   Signature Reserved (signature == "TCPA")
> >         == Trusted Computing Platform Alliance table ==
> >         Optional, not currently supported, and may need changes to fully
> > @@ -266,6 +305,10 @@ WPBT   Signature Reserved (signature == "WPBT")
> >         == Windows Platform Binary Table ==
> >         Microsoft only table, will not be supported.
> >
> > +XENV   Signature Reserved (signature == "XENV")
> > +       == Xen project table ==
> > +       Optional, used only by Xen at present.
> > +
> >  XSDT   Section 5.2.8 (signature == "XSDT")
> >         == eXtended System Description Table ==
> >         Required for arm64.
> > @@ -273,31 +316,57 @@ XSDT   Section 5.2.8 (signature == "XSDT")
> >
> >  ACPI Objects
> >  ------------
> > -The expectations on individual ACPI objects are discussed in the list that
> > -follows:
> > +The expectations on individual ACPI objects that are likely to be used are
> > +shown in the list that follows:
> >
> >  Name   Section         Usage for ARMv8 Linux
> >  ----   ------------    -------------------------------------------------
> > +_ACx   11.4.1          Use as needed.
> > +
> >  _ADR   6.1.1           Use as needed.
> >
> > +_ALx   11.4.2          Use as needed.
> > +
> > +_ART   11.4.3          Use as needed.
> > +
> >  _BBN   6.5.5           Use as needed; PCI-specific.
> >
> > -_BDN   6.5.3           Optional; not likely to be used on arm64.
> > +_CCA   6.2.17          This method must be defined for all bus masters
> > +                       on arm64 -- there are no assumptions made about
> > +                       whether such devices are cache coherent or not.
> > +                       The _CCA value is inherited by all descendants of
> > +                       these devices so it does not need to be repeated.
> > +                       Without _CCA on arm64, the kernel does not know what
> > +                       to do about setting up DMA for the device.
> >
> > -_CCA   6.2.17          This method should be defined for all bus masters
> > -                       on arm64.  While cache coherency is assumed, making
> > -                       it explicit ensures the kernel will set up DMA as
> > -                       it should.
> > +                       NB: this method provides default cache coherency
> > +                       attributes; the presence of an SMMU can be used to
> > +                       modify that, however.  For example, a master could
> > +                       default to non-coherent, but be made coherent with
> > +                       the appropriate SMMU configuration (see Table 17 of
> > +                       the IORT specification, ARM Document DEN 0049B).
> >
> > -_CDM   6.2.1           Optional, to be used only for processor devices.
> > +_CDM   6.2.1           Use as needed, to be used only for processor devices.
> >
> > -_CID   6.1.2           Use as needed.
> > +_CID   6.1.2           Use as needed, see also _HID.
> >
> > -_CLS   6.1.3           Use as needed.
> > +_CLS   6.1.3           Use as needed, see also _HID.
> > +
> > +_CPC   8.4.7.1         Use as needed; power management specific.  CPPC is
> > +                       recommended on arm64.
> > +
> > +_CR3   11.4.5          Use as needed.
> >
> >  _CRS   6.2.2           Required on arm64.
> >
> > -_DCK   6.5.2           Optional; not likely to be used on arm64.
> > +_CRT   11.4.4          Use as needed.
> > +
> > +_CSD   8.4.2.2         Use as needed, used only in conjuction with _CST.
> > +
> > +_CST   8.4.2.1         Low power idle states (8.4.4) are recommended instead
> > +                       of C-states.
> > +
> > +_CWS   9.18.6          Use as needed.
> >
> >  _DDN   6.1.4           This field can be used for a device name.  However,
> >                         it is meant for DOS device names (e.g., COM1), so be
> > @@ -305,11 +374,11 @@ _DDN   6.1.4           This field can be used for a device name.  However,
> >
> >  _DEP   6.5.8           Use as needed.
> >
> > -_DIS   6.2.3           Optional, for power management use.
> > +_DIS   6.2.3           Use as needed, for power management use.
> >
> > -_DLM   5.7.5           Optional.
> > +_DLM   5.7.5           Use as needed.
> >
> > -_DMA   6.2.4           Optional.
> > +_DMA   6.2.4           Use as needed.
> >
> >  _DSD   6.2.5           To be used with caution.  If this object is used, try
> >                         to use it within the constraints already defined by the
> > @@ -325,19 +394,29 @@ _DSD   6.2.5           To be used with caution.  If this object is used, try
> >                         with the UEFI Forum; this may cause some iteration as
> >                         more than one OS will be registering entries.
> >
> > -_DSM                   Do not use this method.  It is not standardized, the
> > +_DSM   9.1.1           Do not use this method.  It is not standardized, the
> >                         return values are not well documented, and it is
> >                         currently a frequent source of error.
> >
> > -_DSW   7.2.1           Use as needed; power management specific.
> > +_DSW   7.3.1           Use as needed; power management specific.
> >
> > -_EDL   6.3.1           Optional.
> > +_DTI   11.4.6          Use as needed.
> >
> > -_EJD   6.3.2           Optional.
> > +_EDL   6.3.1           Use as needed.
> >
> > -_EJx   6.3.3           Optional.
> > +_EJD   6.3.2           Use as needed.
> >
> > -_FIX   6.2.7           x86 specific, not used on arm64.
> > +_EJx   6.3.3           Use as needed.
> > +
> > +_FIF   11.3.1.1        Use as needed.
> > +
> > +_FPS   11.3.1.2        Use as needed.
> > +
> > +_FSL   11.3.1.3        Use as needed.
> > +
> > +_FST   11.3.1.4        Use as needed.
> > +
> > +_GCP   9.18.2          Use as needed.
> >
> >  \_GL   5.7.1           This object is not to be used in hardware reduced
> >                         mode, and therefore should not be used on arm64.
> > @@ -349,35 +428,57 @@ _GLK   6.5.7           This object requires a global lock be defined; there
> >  \_GPE  5.3.1           This namespace is for x86 use only.  Do not use it
> >                         on arm64.
> >
> > -_GSB   6.2.7           Optional.
> > +_GRT   9.18.3          Use as needed.
> > +
> > +_GSB   6.2.7           Use as needed.
> > +
> > +_GTF   9.9.1.1         Use as needed.
> > +
> > +_GWS   9.18.5          Use as needed.
> >
> >  _HID   6.1.5           Use as needed.  This is the primary object to use in
> >                         device probing, though _CID and _CLS may also be used.
> >
> > -_HPP   6.2.8           Optional, PCI specific.
> > +_HOT   11.4.7          Use as needed.
> > +
> > +_HPP   6.2.8           Use as needed, PCI specific.
> >
> > -_HPX   6.2.9           Optional, PCI specific.
> > +_HPX   6.2.9           Use as needed, PCI specific.
> >
> > -_HRV   6.1.6           Optional, use as needed to clarify device behavior; in
> > -                       some cases, this may be easier to use than _DSD.
> > +_HRV   6.1.6           Use as needed, use as needed to clarify device
> > +                       behavior; in some cases, this may be easier to use
> > +                       than _DSD.
> >
> >  _INI   6.5.1           Not required, but can be useful in setting up devices
> >                         when UEFI leaves them in a state that may not be what
> >                         the driver expects before it starts probing.
> >
> > -_IRC   7.2.15          Use as needed; power management specific.
> > +_IRC   7.3.15          Use as needed; power management specific.
> > +
> > +_LCK   6.3.4           Use as needed.
> > +
> > +_LPI   8.4.4.3         Use as needed, but recommended for use with processor
> > +                       definitions (_HID ACPI0010) on arm64.
> >
> > -_LCK   6.3.4           Optional.
> > +_MAT   6.2.10          Use as needed; see also the MADT.
> >
> > -_MAT   6.2.10          Optional; see also the MADT.
> > +_MBM   9.13.2.1        Use as needed.
> >
> > -_MLS   6.1.7           Optional, but highly recommended for use in
> > +_MLS   6.1.7           Use as needed, but highly recommended for use in
> >                         internationalization.
> >
> > -_OFF   7.1.2           It is recommended to define this method for any device
> > +_MSG   9.2.2           Use as needed.
> > +
> > +_MSM   9.13.2.2        Use as needed.
> > +
> > +_MTL   11.4.8          Use as needed.
> > +
> > +_NTT   11.4.9          Use as needed.
> > +
> > +_OFF   7.2.2           It is recommended to define this method for any device
> >                         that can be turned on or off.
> >
> > -_ON    7.1.3           It is recommended to define this method for any device
> > +_ON    7.2.3           It is recommended to define this method for any device
> >                         that can be turned on or off.
> >
> >  \_OS   5.7.3           This method will return "Linux" by default (this is
> > @@ -405,115 +506,219 @@ _OSC   6.2.11          This method can be a global method in ACPI (i.e.,
> >                         being used or what functionality is provided.  The
> >                         _OSC method is to be used instead.
> >
> > -_OST   6.3.5           Optional.
> > +_OST   6.3.5           Use as needed.
> > +
> > +_PCT   8.4.6.1         Use as needed; power management specific.
> >
> >  _PDC   8.4.1           Deprecated, do not use on arm64.
> >
> > +_PDL   8.4.6.2         Use as needed; power management specific.
> > +
> >  \_PIC  5.8.1           The method should not be used.  On arm64, the only
> >                         interrupt model available is GIC.
> >
> > -_PLD   6.1.8           Optional.
> > +_PLD   6.1.8           Use as needed.
> > +
> > +_PPC   8.4.6.3         Use as needed; power management specific.
> > +
> > +_PPE   8.4.8           Use as needed.
> >
> >  \_PR   5.3.1           This namespace is for x86 use only on legacy systems.
> >                         Do not use it on arm64.
> >
> > -_PRS   6.2.12          Optional.
> > +_PRE   7.3.12          Use as needed; power management specific.
> > +
> > +_PRR   7.3.26          Use as needed; power management specific.
> > +
> > +_PRS   6.2.12          Use as needed.
> >
> >  _PRT   6.2.13          Required as part of the definition of all PCI root
> >                         devices.
> >
> > -_PRW   7.2.13          Use as needed; power management specific.
> > +_PRW   7.3.13          Use as needed; power management specific.
> >
> > -_PRx   7.2.8-11        Use as needed; power management specific.  If _PR0 is
> > +_PRx   7.3.8-11        Use as needed; power management specific.  If _PR0 is
> >                         defined, _PR3 must also be defined.
> >
> > -_PSC   7.2.6           Use as needed; power management specific.
> > +_PSC   7.3.6           Use as needed; power management specific.
> > +
> > +_PSD   8.4.6.5         Use as needed; power management specific.
> >
> > -_PSE   7.2.7           Use as needed; power management specific.
> > +_PSE   7.3.7           Use as needed; power management specific.
> >
> > -_PSW   7.2.14          Use as needed; power management specific.
> > +_PSL   11.4.10         Use as needed.
> >
> > -_PSx   7.2.2-5         Use as needed; power management specific.  If _PS0 is
> > +_PSS   8.4.6.2         Use as needed; power management specific.
> > +
> > +_PSV   11.4.11         Use as needed.
> > +
> > +_PSW   7.3.14          Use as needed; power management specific.
> > +
> > +_PSx   7.3.2-5         Use as needed; power management specific.  If _PS0 is
> >                         defined, _PS3 must also be defined.  If clocks or
> >                         regulators need adjusting to be consistent with power
> >                         usage, change them in these methods.
> >
> > -\_PTS  7.3.1           Use as needed; power management specific.
> > +_PTC   8.4.5.1         Use as needed; power management specific.
> > +
> > +\_PTS  7.4.1           Use as needed; power management specific.
> > +
> > +_PUR   8.5.1.1         Use as needed.
> > +
> > +_PXM   6.2.14          Use as needed.
> >
> > -_PXM   6.2.14          Optional.
> > +_RDI   8.4.4.4         Use as needed, but recommended for use with processor
> > +                       definitions (_HID ACPI0010) on arm64.
> >
> 
> Should we also mention here that _RDI used only in conjuction with _LPI.
> 
> Because as per section 8.4.4.4 "The dependency between the power
> resources and the LPI state is described in _RDI"
> 
> >  _REG   6.5.4           Use as needed.
> >
> >  \_REV  5.7.4           Always returns the latest version of ACPI supported.
> >
> > -_RMV   6.3.6           Optional.
> > +_RMV   6.3.6           Use as needed.
> > +
> > +_RST   7.3.25          Use as needed; power management specific.
> > +
> > +_RTV   11.4.12         Use as needed.
> >
> >  \_SB   5.3.1           Required on arm64; all devices must be defined in this
> >                         namespace.
> >
> > +_SCP   11.4.13         Use as needed.
> > +
> > +_SDD   9.9.3.3.1       Use as needed.
> > +
> >  _SEG   6.5.6           Use as needed; PCI-specific.
> >
> > -\_SI   5.3.1,          Optional.
> > -       9.1
> > +\_SI   5.3.1,          Use as needed.
> > +       9.2
> > +
> > +_SLI   6.2.15          Use as needed; recommended when SLIT table is in use.
> >
> > -_SLI   6.2.15          Optional; recommended when SLIT table is in use.
> > +_SRT   9.18.4          Use as needed.
> >
> >  _STA   6.3.7,          It is recommended to define this method for any device
> > -       7.1.4           that can be turned on or off.
> > +       7.2.4           that can be turned on or off.  See also the STAO table
> > +                       that provides overrides to hide devices in virtualized
> > +                       environments.
> >
> > -_SRS   6.2.16          Optional; see also _PRS.
> > +_SRS   6.2.16          Use as needed; see also _PRS.
> > +
> > +_SST   9.2.1           Use as needed.
> >
> >  _STR   6.1.10          Recommended for conveying device names to end users;
> >                         this is preferred over using _DDN.
> >
> > +_SST   9.2.1           Use as needed.
> > +
> > +_STP   9.18.7          Use as needed.
> > +
> > +_STV   9.18.8          Use as needed.
> > +
> >  _SUB   6.1.9           Use as needed; _HID or _CID are preferred.
> >
> > -_SUN   6.1.11          Optional.
> > +_SUN   6.1.11          Use as needed, but recommended.
> >
> > -\_Sx   7.3.2           Use as needed; power management specific.
> > +\_Sx   7.4.2           Use as needed; power management specific.
> >
> > -_SxD   7.2.16-19       Use as needed; power management specific.
> > +_SxD   7.3.16-19       Use as needed; power management specific.
> >
> > -_SxW   7.2.20-24       Use as needed; power management specific.
> > +_SxW   7.3.20-24       Use as needed; power management specific.
> >
> > -_SWS   7.3.3           Use as needed; power management specific; this may
> > +_SWS   7.4.3           Use as needed; power management specific; this may
> >                         require specification changes for use on arm64.
> >
> > -\_TTS  7.3.4           Use as needed; power management specific.
> > +_TC1   11.4.14         Use as needed.
> > +
> > +_TC2   11.4.15         Use as needed.
> > +
> > +_TDL   8.4.5.5         Use as needed; power management specific.
> > +
> > +_TFP   11.4.16         Use as needed.
> > +
> > +_TIP   9.18.9          Use as needed.
> > +
> > +_TIV   9.18.10         Use as needed.
> > +
> > +_TMP   11.4.17         Use as needed.
> > +
> > +_TPC   8.4.5.3         Use as needed; power management specific.
> >
> > -\_TZ   5.3.1           Optional.
> > +_TPT   11.4.18         Use as needed.
> > +
> > +_TRT   11.4.19         Use as needed.
> > +
> > +_TSD   8.4.5.4         Use as needed; power management specific.
> > +
> > +_TSN   11.4.20         Use as needed.
> > +
> > +_TSP   11.4.21         Use as needed.
> > +
> > +_TSS   8.4.5.2         Use as needed; power management specific.
> > +
> > +_TST   11.4.22         Use as needed.
> > +
> > +\_TTS  7.4.4           Use as needed; power management specific.
> > +
> > +\_TZ   5.3.1           Use as needed.
> > +
> > +_TZD   11.4.23         Use as needed.
> > +
> > +_TZM   11.4.24         Use as needed.
> > +
> > +_TZP   11.4.25         Use as needed.
> >
> >  _UID   6.1.12          Recommended for distinguishing devices of the same
> >                         class; define it if at all possible.
> >
> > -\_WAK  7.3.5           Use as needed; power management specific.
> > +_UPC   9.14            Use as needed.
> > +
> > +\_WAK  7.4.5           Use as needed; power management specific.
> > +
> > +
> >
> >
> >  ACPI Event Model
> >  ----------------
> >  Do not use GPE block devices; these are not supported in the hardware reduced
> >  profile used by arm64.  Since there are no GPE blocks defined for use on ARM
> > -platforms, GPIO-signaled interrupts should be used for creating system events.
> > +platforms, ACPI events must be signaled differently.
> > +
> > +There are two options: GPIO-signaled interrupts (Section 5.6.5), and
> > +interrupt-signaled events (Section 5.6.9).  Interrupt-signaled events are a
> > +new feature in the ACPI 6.1 specification.  Either -- or both -- can be used
> > +on a given platform, and which to use may be dependent of limitations in any
> > +given SoC.  If possible, interrupt-signaled events are recommended.
> >
> >
> >  ACPI Processor Control
> >  ----------------------
> > -Section 8 of the ACPI specification is currently undergoing change that
> > -should be completed in the 6.0 version of the specification.  Processor
> > -performance control will be handled differently for arm64 at that point
> > -in time.  Processor aggregator devices (section 8.5) will not be used,
> > -for example, but another similar mechanism instead.
> > -
> > -While UEFI constrains what we can say until the release of 6.0, it is
> > -recommended that CPPC (8.4.5) be used as the primary model.  This will
> > -still be useful into the future.  C-states and P-states will still be
> > -provided, but most of the current design work appears to favor CPPC.
> > +Section 8 of the ACPI specification changed significantly in version 6.0.
> > +Processors should now be defined as Device objects with _HID ACPI0007; do
> > +not use the deprecated Processor statement in ASL.  All multiprocessor systems
> > +should also define a hierarchy of processors, done with Processor Container
> > +Devices (see Section 8.4.3.1, _HID ACPI0010); do not use processor aggregator
> > +devices (Section 8.5) to describe processor topology.  Section 8.4 of the
> > +specification describes the semantics of these object definitions and how
> > +they interrelate.
> > +
> > +Most importantly, the processor hierarchy defined also defines the low power
> > +idle states that are available to the platform, along with the rules for
> > +determining which processors can be turned on or off and the circumstances
> > +that control that.  Without this information, the processors will run in
> > +whatever power state they were left in by UEFI.
> > +
> > +Note too, that the processor Device objects defined and the entries in the
> > +MADT for GICs are expected to be in sychronization.  The _UID of the Device
> > +object must correspond to processor IDs used in the MADT.
> > +
> > +It is recommended that CPPC (8.4.5) be used as the primary model for processor
> > +performance control on arm64.  C-states and P-states may become available at
> > +some point in the future, but most current design work appears to favor CPPC.
> >
> >  Further, it is essential that the ARMv8 SoC provide a fully functional
> >  implementation of PSCI; this will be the only mechanism supported by ACPI
> > -to control CPU power state (including secondary CPU booting).
> > -
> > -More details will be provided on the release of the ACPI 6.0 specification.
> > +to control CPU power state.  Booting of secondary CPUs may be possible using
> > +parking protocol, but only PSCI is to be used for ARM servers.
> >
> >
> >  ACPI System Address Map Interfaces
> > @@ -535,21 +740,25 @@ used to indicate fatal errors that cannot be corrected, and require immediate
> >  attention.
> >
> >  Since there is no direct equivalent of the x86 SCI or NMI, arm64 handles
> > -these slightly differently.  The SCI is handled as a normal GPIO-signaled
> > -interrupt; given that these are corrected (or correctable) errors being
> > -reported, this is sufficient.  The NMI is emulated as the highest priority
> > -GPIO-signaled interrupt possible.  This implies some caution must be used
> > -since there could be interrupts at higher privilege levels or even interrupts
> > -at the same priority as the emulated NMI.  In Linux, this should not be the
> > -case but one should be aware it could happen.
> > +these slightly differently.  The SCI is handled as a high priority interrupt;
> > +given that these are corrected (or correctable) errors being reported, this
> > +is sufficient.  The NMI is emulated as the highest priority interrupt
> > +possible.  This implies some caution must be used since there could be
> > +interrupts at higher privilege levels or even interrupts at the same priority
> > +as the emulated NMI.  In Linux, this should not be the case but one should
> > +be aware it could happen.

Unrelated to the patch content or to your reply (which I couldn't find
even after scrolling up and down a few times): please trim the original
message and only quote the relevant text, it would make following a
discussion much easier.

(I haven't trimmed it either and I randomly placed my reply, just to
make a point)

> >
> >
> >  ACPI Objects Not Supported on ARM64
> >  -----------------------------------
> >  While this may change in the future, there are several classes of objects
> >  that can be defined, but are not currently of general interest to ARM servers.
> > +Some of these objects have x86 equivalents, and may actually make sense in ARM
> > +servers.  However, there is either no hardware available at present, or there
> > +may not even be a non-ARM implementation yet.  Hence, they are not currently
> > +supported.
> >
> > -These are not supported:
> > +The following classes of objects are not supported:
> >
> >         -- Section 9.2: ambient light sensor devices
> >
> > @@ -571,16 +780,6 @@ These are not supported:
> >
> >         -- Section 9.18: time and alarm devices (see 9.15)
> >
> > -
> > -ACPI Objects Not Yet Implemented
> > ---------------------------------
> > -While these objects have x86 equivalents, and they do make some sense in ARM
> > -servers, there is either no hardware available at present, or in some cases
> > -there may not yet be a non-ARM implementation.  Hence, they are currently not
> > -implemented though that may change in the future.
> > -
> > -Not yet implemented are:
> > -
> >         -- Section 10: power source and power meter devices
> >
> >         -- Section 11: thermal management
> > @@ -589,5 +788,31 @@ Not yet implemented are:
> >
> >         -- Section 13: SMBus interfaces
> >
> > -       -- Section 17: NUMA support (prototypes have been submitted for
> > -          review)
> > +
> > +This also mean that there is no support for the following objects:
> > +
> > +Name   Section                     Name   Section
> > +----   ------------                ----   ------------
> > +_ALC   9.3.4                       _FDM   9.10.3
> > +_ALI   9.3.2                       _FIX   6.2.7
> > +_ALP   9.3.6                       _GAI   10.4.5
> > +_ALR   9.3.5                       _GHL   10.4.7
> > +_ALT   9.3.3                       _GTM   9.9.2.1.1
> > +_BCT   10.2.2.10                   _LID   9.5.1
> > +_BDN   6.5.3                       _PAI   10.4.4
> > +_BIF   10.2.2.1                    _PCL   10.3.2
> > +_BIX   10.2.2.1                    _PIF   10.3.3
> > +_BLT   9.2.3                       _PMC   10.4.1
> > +_BMA   10.2.2.4                    _PMD   10.4.8
> > +_BMC   10.2.2.12                   _PMM   10.4.3
> > +_BMD   10.2.2.11                   _PRL   10.3.4
> > +_BMS   10.2.2.5                    _PSR   10.3.1
> > +_BST   10.2.2.6                    _PTP   10.4.2
> > +_BTH   10.2.2.7                    _SBS   10.1.3
> > +_BTM   10.2.2.9                    _SHL   10.4.6
> > +_BTP   10.2.2.8                    _STM   9.9.2.1.1
> > +_DCK   6.5.2                       _UPD   9.16.1
> > +_EC    12.12                       _UPP   9.16.2
> > +_FDE   9.10.1                      _WPC   10.5.2
> > +_FDI   9.10.2                      _WPP   10.5.3
> > +
> > diff --git a/Documentation/arm64/arm-acpi.txt b/Documentation/arm64/arm-acpi.txt
> > index 570a4f8..12381c1 100644
> > --- a/Documentation/arm64/arm-acpi.txt
> > +++ b/Documentation/arm64/arm-acpi.txt
> > @@ -57,11 +57,11 @@ The short form of the rationale for ACPI on ARM is:
> >
> >  -- The new ACPI governance process works well and Linux is now at the same
> >     table as hardware vendors and other OS vendors.  In fact, there is no
> > -   longer any reason to feel that ACPI is only belongs to Windows or that
> > +   longer any reason to feel that ACPI only belongs to Windows or that
> >     Linux is in any way secondary to Microsoft in this arena.  The move of
> >     ACPI governance into the UEFI forum has significantly opened up the
> >     specification development process, and currently, a large portion of the
> > -   changes being made to ACPI is being driven by Linux.
> > +   changes being made to ACPI are being driven by Linux.
> >
> >  Key to the use of ACPI is the support model.  For servers in general, the
> >  responsibility for hardware behaviour cannot solely be the domain of the
> > @@ -159,7 +159,7 @@ Further, the ACPI core will only use the 64-bit address fields in the FADT
> >  (Fixed ACPI Description Table).  Any 32-bit address fields in the FADT will
> >  be ignored on arm64.
> >
> > -Hardware reduced mode (see Section 4.1 of the ACPI 5.1 specification) will
> > +Hardware reduced mode (see Section 4.1 of the ACPI 6.1 specification) will
> >  be enforced by the ACPI core on arm64.  Doing so allows the ACPI core to
> >  run less complex code since it no longer has to provide support for legacy
> >  hardware from other architectures.  Any fields that are not to be used for
> > @@ -167,7 +167,7 @@ hardware reduced mode must be set to zero.
> >
> >  For the ACPI core to operate properly, and in turn provide the information
> >  the kernel needs to configure devices, it expects to find the following
> > -tables (all section numbers refer to the ACPI 5.1 specfication):
> > +tables (all section numbers refer to the ACPI 6.1 specfication):
> >
> >      -- RSDP (Root System Description Pointer), section 5.2.5
> >
> > @@ -185,9 +185,22 @@ tables (all section numbers refer to the ACPI 5.1 specfication):
> >      -- If PCI is supported, the MCFG (Memory mapped ConFiGuration
> >         Table), section 5.2.6, specifically Table 5-31.
> >
> > +    -- If booting without a console=<device> kernel parameter is
> > +       supported, the SPCR (Serial Port Console Redirection table),
> > +       section 5.2.6, specifically Table 5-31.
> > +
> > +    -- If virtualization is supported, the IORT (Input Output Remapping
> > +       Table, section 5.2.6, specifically Table 5-31.
> > +
> > +    -- If NUMA is supported, the SRAT (System Resource Affinity Table)
> > +       and SLIT (System Locality distance Information Table), sections
> > +       5.2.16 and 5.2.17, respectively.
> > +
> >  If the above tables are not all present, the kernel may or may not be
> >  able to boot properly since it may not be able to configure all of the
> > -devices available.
> > +devices available.  This list of tables is not meant to be all inclusive;
> > +in some environments other tables may be needed (e.g., any of the APEI
> > +tables from section 18) to support specific functionality.
> >
> >
> >  ACPI Detection
> > @@ -233,7 +246,7 @@ that looks like this: Name(KEY0, "value0").  An ACPI device driver would
> >  then retrieve the value of the property by evaluating the KEY0 object.
> >  However, using Name() this way has multiple problems: (1) ACPI limits
> >  names ("KEY0") to four characters unlike DT; (2) there is no industry
> > -wide registry that maintains a list of names, minimzing re-use; (3)
> > +wide registry that maintains a list of names, minimizing re-use; (3)
> >  there is also no registry for the definition of property values ("value0"),
> >  again making re-use difficult; and (4) how does one maintain backward
> >  compatibility as new hardware comes out?  The _DSD method was created
> > @@ -434,7 +447,8 @@ The ACPI specification changes regularly.  During the year 2014, for instance,
> >  version 5.1 was released and version 6.0 substantially completed, with most of
> >  the changes being driven by ARM-specific requirements.  Proposed changes are
> >  presented and discussed in the ASWG (ACPI Specification Working Group) which
> > -is a part of the UEFI Forum.
> > +is a part of the UEFI Forum.  The current version of the ACPI specification
> > +is 6.1 release in January 2016.
> >
> >  Participation in this group is open to all UEFI members.  Please see
> >  http://www.uefi.org/workinggroup for details on group membership.
> > --
> > 2.5.0
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